Nixon spoke after police used tear gas and smoke bombs to repel protesters after another night of chaos in the St. Louis suburb. Nixon said that "operational shifts" were in the works and "a different tone" would be set by police offers who were dealing with a community outraged by the shooting death.

Two reporters said they were detained by police for not clearing out quickly enough from a McDonald's where they were working, near the protests but away from the more volatile areas. The two, who work for The Washington Post and The Huffington Post, were released without any charges. Both say they were assaulted but not seriously hurt.

St. Louis County police spokesman Brian Schellman said officers on Wednesday night tossed tear gas to disperse a large crowd of protesters after some threw Molotov cocktails and rocks at officers. More than 10 people were arrested in Ferguson.

"In talking to these guys, it is scary," Schellman said of officers on the front lines of the protest. "They hear gunshots going off, and they don't know where they're coming from."

But the police response is drawing criticism from many circles. Civil rights activist Al Sharpton called Thursday for the Justice Department to monitor Ferguson and the way police are handling the crisis.

"Even if we disagree, this climate is not good for anyone and is dangerous for everyone," Sharpton said in a statement.

The police chiefs of Ferguson and St. Louis County said Wednesday that race relations were the top priority in the town, where a white police officer fatally shot the black teen. Authorities have vowed to reach across the racial, economic and generational divide in a community in search of answers. A meeting was scheduled for Thursday between civil rights leaders and police.

Officers from multiple departments in riot gear and in military equipment have clashed nightly with protesters, who chant, "Hands up, don't shoot." Protesters faced heavily armed police who at times trained weapons on them from armored trucks.

CBS St. Louis affiliate KMOV-TV reports that the arrests included St. Louis Alderman Antonio French, who has been chronicling the protests on social media.

"I think the heavy-handed approach by police is escalating the situation and more people are going to get hurt if this keeps up," French told KMOX Radio.